View full sizeWilliam Neff, The PDCLEVELAND, Ohio, -- Even a small increase in the plaque that can build up on artery walls in the heart leads to more heart attacks, bypass surgery, angioplasty and deaths, according to a study published Tuesday by Cleveland Clinic researchers.

The group examined results from six Clinic-led trials that used a technology called intravascular ultrasound (IVUS) to measure plaque buildup in the arteries of 4,317 patients with heart disease.

Plaque growth of less than 1 percent over an 18 to 24 month period predicted poor outcomes for patients, said Dr. Steven Nissen, the Clinic's chief of cardiovascular medicine and an author on the paper.

The difference in plaque growth between patients that had major adverse events (heart attack, bypass or angioplasty surgeries, and death) and those that did not was only 0.5 percent.

"These little changes are obviously having a magnified effect on outcome," Nissen said.

Dr. Gurpreet Sandhu, interventional cardiologist at the Mayo Clinic in Minnesota, said the study confirms a wealth of existing data that shows that increased plaque volume and disease progression leads to adverse outcomes in patients.

"It's therefore very important from a patient perspective to control all their risk factors -- especially their cholesterol -- to reduce their long term chances of getting heart disease," he said.

Nissen said the group's findings are particularly important in the context of clinical trials, many of them led by the Clinic, that measure the effects of cholesterol-lowering drugs called statins on the volume of plaque in heart arteries.

"The differences in [plaque volume] progression rates for treatments we've tested were really very small -- they were fractions of 1 percent," said Nissen, who helped develop IVUS at the Clinic in the mid-1980's. "We now know that very small differences in therapy, that slow this disease a little bit, translate into pretty significant differences in clinical outcome."

IVUS provides a 360-degree, sectioned view of the inside of an arterial wall by inserting a tiny catheter into the vessel that bounces high frequency sound waves off the surrounding tissue. It is used widely in research and during stent placement and other cardiac procedures.

The Clinic has been at the forefront of clinical trials using IVUS for the assessment of the progression of coronary artery disease. It is currently leading a study of 1,300 patients that compares cholesterol-lowering drugs Crestor and Lipitor, to see which is better at shrinking plaque. Results should be available in 2011.

Dr. Armin Zadeh, associate director of cardiac computed tomography at Johns Hopkins Hospital, said Monday that while the current study is important, he isn't sure that IVUS is the best tool for assessing the efficacy of cardiac treatments.

"IVUS is an invasive tool, and it has a huge disadvantage because it requires cardiac catheterization," he said. Zadeh uses computed tomography, a technique that uses X-rays to take pictures of the heart.

Sandhu said that IVUS is expensive and invasive, but he believes it can play an important role in clinical trials, where small numbers of carefully selected patients are involved.

"As a research tool to study the effects of new medications and therapies, this would be quite valuable," he said.

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